


A Waste of Talent

by VictoriaHolmesWriting



Series: The Baker Street Wizards [1]
Category: Harry Potter - J. K. Rowling, Sherlock (TV)
Genre: Alternate Universe, And Tons of Sass, Angst, Brief Suggestive Language, Crossover, Death, Explicit Language, Gen, Implied/Referenced Drug Use, John and Sherlock are wizards, Original Female Character - Freeform, Original Male Character - Freeform, PTSD, Plenty of banter, Poison, Post Wizarding War, Potions, Snape lives au
Language: English
Status: Completed
Published: 2019-07-29
Updated: 2019-12-29
Packaged: 2020-07-25 19:04:05
Rating: Mature
Warnings: Graphic Depictions Of Violence
Chapters: 14
Words: 12,183
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20030824
Author URL: https://archiveofourown.org/users/VictoriaHolmesWriting/pseuds/VictoriaHolmesWriting
Summary: A case with a mystery potion leads Sherlock and John to team up with their old Potions Master





	1. The Quaffle

**Author's Note:**

> Many thanks to JosieCarioca for requesting a Snape/Sherlock case solving crossover! This is so fun to write!
> 
> Go read her series, Post-War! It's brilliant!!!

John Watson nearly dropped his tea as he stared at his best friend, Sherlock Holmes. He quickly put it on the little table by his chair, trying to fathom what in the hell the detective had just asked him.

Sherlock waited impatiently for him to answer.

The blogger shook his head as if he thought there was something in his ears impairing his hearing. “I’m sorry, I’m going to need you to say that again,” he implored, an uncertain laugh on his breath.

Groaning dramatically, complete with an award worthy eye roll, Sherlock snatched up the odd, dented red ball from his own chair. “What is _this_ used for?” he repeated, not caring to hide his annoyance. He hated repeating himself, especially when it was a question he didn’t know the answer to.

His scowl intensified exponentially as the sight of John’s smirk.

“Are you serious?”

“Just answer the damn question,” Sherlock growled, giving his only friend a death stare that would have sent anyone else running for the hills.

But John was not anyone else and he was going to revel in this moment. He pointed at the large ball in Sherlock’s hands. “That’s a Quaffle, Sherlock. I thought that was fairly obvious.”

“And _what_ is the Quaffle for?” he demanded, choosing not to acknowledge the ironic dig at his intelligence.

Sherlock tossed the Quaffle roughly to John -- who caught it to his chest without blinking. His glare lightened by a fraction, the brow furrow shifting in meaning as he tried to deduce the effortless catch.

“It’s for quidditch,” John explained in a voice that was equally condescending and astonished.  
Sherlock rolled his eyes again, somehow out doing his last performance, and dropped haphazardly into his chair with a drawn out sigh.

“How can you not know anything about quidditch?” John continued. “You went to Hogwarts!”  
Sherlock actually growled. This was the solar system argument all over again.

“What does it matter?” he fired back, all patience gone. “It’s just people aggressively flying around on broomsticks while other people pretend to know what the hell is going on!”

John pinched the bridge of his nose. “What did you do during the House matches?” he asked, dropping his tone. He knew Sherlock was at the end of his rope and decided not to directly antagonize him anymore.

This has the desired effect as Sherlock’s shoulders (and his pout) relaxed. “I enjoyed the peace and quiet of the empty castle in the library or my common room.”

John laughed, eliciting a hurt look from Sherlock. He put his hands up. “I’m not laughing at you! I just can’t believe I never thought to skip a Hufflepuff match every once in a while. Merlin, they were rubbish during my years!”

“Don’t insult Hufflepuff too loudly,” Sherlock smirked. “Mrs. Hudson will starve us for a week if she hears you.”

They both laughed, knowing full well how true that statement was.

“You’re lucky she is a Badger,” he went on, “or else she might not have so easily forgiven you for assuming she’s a Muggle.”

“Yeah, but I’d rather not push my luck,” the other replied honestly.

Sherlock’s chuckle vibrated from his chest.

Before either of them could say anything else, a ding and buzz sounded from Sherlock’s phone.  
John watched closely, trying not to be obvious in his hopeful excitement as Sherlock practically leapt across the room to grab the phone off the couch. He’d thrown it there earlier that morning in a fit of boredom. To be honest, it had been so long since their last interesting case they were both on edge.

Excitement burst into Sherlock’s eyes when he read the brief text from Detective Lestrade.

_3 dead. Weird poison. No leads. Interested?_

He grabbed his coat and ran out the door of 221b, John right behind him.


	2. Lestrade's Relief

**Summary for the Chapter:**

> Lestrade debriefs them on the case

D.I. Lestrade sat at his desk eating a glazed donut and re-examining the crime scene notes. Donovan and Anderson were rambling on -- well, more like ranting -- about the details of the case and the unexplained poison, but Lestrade wasn’t listening. He didn’t need the genius deductive skills of Sherlock Holmes to know they had nothing and were merely stalling. This happened every time he brought Sherlock and John in on a case. He no longer had any patience for their jealousy and honestly wished they weren’t so under-staffed as he would gladly be rid of them.

He looked up at the sound of footsteps approaching and honestly could have hugged both of the men that entered his office.

“Oh, thank God!” he exclaimed as they made their way in.

With a nasty sneer on his face, Anderson opened his mouth to say something no doubt cruel. He quickly closed it again, however, when he noticed John’s glare.

Sherlock locked eyes with Lestrade as he coldly remarked, “There seems to be too many people in the room, Lestrade. The level of stupid is _suffocating_.” His baritone voice dropped lower to carefully emphasize the last word. 

Lestrade snapped his fingers at Donovan and Anderson. “Out!” he barked.

The rejected duo scowled as they stormed out of the room, slamming the door.

As soon as the latch clicked, Sherlock held out his hand for the case file.

“As I said in my text,” Lestrade started, handing it over, “we have three bodies all with the substance we found at the crime scene in their systems. Problem is, no one can figure out what in the hell the substance is. We believe it’s what killed them, but -- as we can’t identify it -- it’s only a theory.”

“Why didn’t you call me in sooner?” Sherlock interrupted, clearly annoyed. He momentarily looked up from the file to give Lestrade a scathing look.

John, who had been making notes as Lestrade debriefed them (as was their routine), frowned reproachfully at his friend, but said nothing. He had long since gotten used to Sherlock’s abrasive personality personality. And he knew that if anyone could brush it off as easily as himself, it was Lestrade. The poor man had put up with Sherlock’s ego and lack of social skills far longer than John had, though he seemed to only have room in his mind palace for one of their given names.

The detective inspector sighed. “Are the bags under my eyes _that_ obvious?” He was definitely used to Sherlock, too. 

Before Sherlock could say anything else, he continued, “We kept waiting to figure out something -- anything -- about what is in the mystery substance. Anderson insisted he could get the results, but -- as usual -- relying on him was a mistake.” Lestrade paused to take a deep breathe. He shook his head. “But you’re here now, so what do you think?”

Lestrade’s tired eyes pleaded for Sherlock to say that he’d take the case. But, for once, Sherlock did not comment on or even notice his desperation. There was no cocky smile or condescending remark. He didn’t even insult Anderson, which Lestrade had honestly been looking forward to. In fact, he wasn’t even blinking.

Sherlock stood ramrod-straight, eyes glued to the paperwork in his hands. Lestrade’s brow furrowed deeper.

Noticing the taller man’s odd behaviour as well, John moved to look at what had caught his attention.

There were several pages with childish handwriting scrawled across them. More notable was the sheer amount of things that were crossed out. The lines were deep and the pages were torn in some places. Anderson’s frustration was far more clearly on the pages than any of the words. The ones he could make out made absolutely no sense to the doctor.

“I need everything you have on this case, including any and all samples you have of this substance. And _no one_ is Scotland Yard is to go anywhere near this case until I have solved it,” Sherlock order at a rapid-fire rate, his eyes snapping to meet Lestrade’s. His tone and the look in his eyes mode it clear he wasn’t going to take no for an answer.

Having no clue what Sherlock was no about, John folded his arms and looked at Lestrade, waiting for him to concede to the demands. Even when he didn’t know Sherlock’s reasons, he trusted the man had them.

At least, he hoped he did.

Lestrade nodded, looking both slightly concerned and elated at the same time.

“Of course! I’ll have all of it sent to Baker Street immediately.” He grabbed the phone as he spoke, into which he was now barking orders.

Sherlock didn’t waste any time in turning on his heel and rushing out of Scotland Yard. John said nothing as he followed him until they were out of the building and away from any nosy officers.

“What was that about?” he asked finally, both of them stopping on the curb.

Sherlock handed him the case file before holding out his arm to flag down a cab. “It’s not just a poison, John,” he said. A slightly manic, excited look growing in the eyes that leveled with John’s. He lowered his voice slightly, but the glee that came with any case that promised to entertain the man was quite plain. “It’s a potion, John The killer is a wizard!”


	3. Confirming a Location

**Summary for the Chapter:**

> Sherlock makes an unpleasant call

**Notes for the Chapter:**

> This chapter is quite a bit shorter than I normally prefer, but it felt necessary that this one be set apart from the previous one.

For the whole of the next week, Sherlock stood over his cauldron at the kitchen table breaking down the potion to its root ingredients. He figured out right away that it was highly advanced -- and completely experimental. Not to mention the fact of the potion consisting largely of extremely illegal materials.

Meanwhile, John poured over the case files and interviewed friends and family. He’d discovered that all three of the victim’s were wizards as well. All had been Gryffindors in the same year and had been close friends. Two had since married each other, and the third was often around. There was absolutely nothing out of the ordinary on the night of the murders or in the weeks leading up to it.

Lestrade was right; they had absolutely nothing.

Mrs. Hudson occasionally ventured upstairs to get them to eat and have tea. As usual, John was far more compliant than Sherlock, but enough nagging and guilt-tripping would get him to eat just so she’d go away. John knew she did this on purpose and loved her so much for it.

Finally, at 2 a.m. on the eighth day, Sherlock added the last ingredient to his list with a shaking hand. He killed the cauldron’s flame with an absentminded flick of his wrist as he brought his hands up to cover and rub his tired, strained eyes. He made a loud groaning sound into his palms before dropping them and snatched up the list.

John woke with a start in his chair where he’d fallen asleep not even an hour ago. Everything they had on the case was scattered in his lap and on the floor in front of him.

“Come on, John!” Sherlock shouted louder than he meant to. He gave his head a rough shake before continuing towards the door.

“Where are we going?” John asked, stumbling as he stood and rubbing the sleep from his own eyes. But Sherlock had already swung on his coat and was halfway down the stairs.

Cursing, he grabbed his own jacket and rushed after him.

Sherlock was very nearly breaking his phone as he dialed in a number when John caught up to him. By the looks of it, they were heading to a Disapparation point, but John had no clue where they might be going. Though, given the aggressive way he was handling his phone, neither did Sherlock.

He only got this angry, unprovoked, when his arch enemy had information he couldn’t get on his own.

“Does Snape still live in that cottage in Wales?” Sherlock demanded through his teeth the moment the other end picked up. He was red in the face and his lip was twitching into a snarl.

John’s eyes widened at the name of his old Potions Master. No one had heard from him since the end of the Second Wizarding War and John had no idea why Sherlock would know where he’d gone.

“Good morning to you, too, brother mine,” Mycroft sneered. His voice was thick and scratchy. “Why the hell are you calling me to ask about Snape at this ungodly hour? Is your memory so weak that you can’t remember the safe house you set up?

The muscles in Sherlock’s jaw flexed and he was turning a dangerous shade of red. John was rapidly becoming more worried that Sherlock might accidentally blow up the alley bins...again.

“I know where it is, Mycroft! But that was fifteen years ago. Which is why I used the word ‘_still!_’” He was pacing now, his long legs beating a path into the concrete. Small, purple sparks were crackling around the fingertips of his free hand, which he was flexing incessantly.

Mycroft tried to retort, but his little brother was tired of his games.

“_Brother mine_,” he spit, “I’m dealing with a wizard serial killer with Potions skills that might actually put a smile on his old, bitter face. Now, where does he live?!”

There was a moment of silence before Mycroft quietly responded, “He’s still there.”

Sherlock ended the call without another word. He grabbed John by the elbow -- far gentler than the shorter man might have expected -- and Disapparated.


	4. A Hint of Familiarity

**Summary for the Chapter:**

> Sherlock leads John to Snape's home and John has many questions.

**Notes for the Chapter:**

> Sorry this chapter took so long. Life has been a bit hectic, but it will hopefully slow down in the near-ish future so I will be able to focus more on my writing.

They appeared in a small clearing in the middle of a dense forest. The ground squelched beneath their feet as they looked around, getting their bearings. Thunder rumbled from somewhere nearby in the dense darkness.

“Where are we?” John asked, trying to squint through the trees. He clutched at his queasy stomach with one arm. He hated Apparating and usually insisted on a broom. But, given Sherlock’s current mood, he didn’t think complaining about it completely necessary.

Sherlock was still fuming from his conversation with the elder Holmes. He stood still, looking around as his eyes adjusted to the dark.

“Wales,” he replied. There was still an edge to his voice, but he was obviously trying to calm down. “After the war, Snape was exonerated thanks to Harry Potter’s testimony that he was indeed working under Dumbledore’s orders. However, there are still many on both sides that aren’t too pleased with him. McGonagall offered him his old position, but he refused -- both because he loathed the job, as you probably well know, and because he knew parents would be furious.

“It was decided that the best thing was to relocate him to somewhere no one would know who he is and the location would be kept secret. I helped Mycroft and others in the Ministry to set it up. As well as to escort him there.”

Finally spotting the landmark he was looking for -- a star-shaped scorch mark in an ancient looking oak tree -- Sherlock moved towards the path he knew to be exactly twenty meters past it “This way, John,” he said quietly, looking back to make sure the other was following.

John stuck close, constantly looking around and taking in everything his limited range of vision would allow.

Neither spoke as they made their way towards the path. There were limbs and rocks everywhere on the forest floor, making it necessary for the two Londoners to concentrate on their footsteps. Each tripped once or twice, but managed to get to the path without completely wiping out.

Sherlock immediately pivoted left down the path, settling into a brisk pace. John noticed that he was falling into autopilot in the same manner as when he walked to his favourite chip shop or back to Baker Street from Scotland Yard. Sherlock had clearly walked with path countless times to the point of setting it to muscle memory. More importantly, he had kept the information logged in his mind palace.

_He knew he would come back someday, _ John realized.

An owl hooted from a high branch overhead as they veered to the right with the bend in the path.

“I’m guessing this is a primarily Muggle village if nobody knows Severus Snape has been here all these years,” John observed. He squinted at the path he only knew was dirt because he could feel it beneath his shoes. “And why we can’t use our wands to see where the bloody hell we’re going.”

"I know where I’m going,” Sherlock snapped. He was still a bit touchy after his conversation with Mycroft. Hearing the harshness in his tone, he gave John an apologetic look he hoped he could see. “But, yes,” he continued in a much nicer tone. “It’s one of the reasons this area was chosen to hide him away from the Wizarding World and allow him some of the peace he’d never been permitted before.”

His choice of words were odd and specific. Something in them hinted towards, what? Familiarity? Sympathy, even? Sherlock wasn’t exactly the type for sympathy. It’s an emotion he’s learned quite recently and he’s still not very good at it, though he tries his best when it concerns one of the few people that managed to get close to him.

So why did it truly sound like Sherlock felt sympathy for his old professor?

Sherlock knew John registered this accidental slip of emotion by his silence. He waited for John’s understandable amount of questions, but John said nothing.

After snapping his head to look at Sherlock in mild shock, he focused his eyes back on the trail in front of him. He definitely had many questions, but this was not the time for them.

Sherlock breathed a quiet sigh of relief.

“How much farther?” John asked after a few moments of silent hiking.

They had finally broken free from the dense forest and were now staring around at the rolling green hills. Well, they assumed the hills were green. The cloudy, moonless night made the fields almost as suffocatingly dark as the forest.

Sherlock pointed towards the far end of the field to the east.

A small cottage, partially tucked into the trees where the forest continued, dented the monotony of the darkness with a soft, warm light coming from a downstairs window. It was the only light in the area. Not surprising, given it was well after midnight and most sane people were in bed.

“Still nocturnal?” John asked rhetorically, referring to the former professor’s reputation as the “dungeon bat.” “Maybe those rumours are true. Maybe Snape is a _vampire._”

Sherlock rolled his eyes, sighing far more audibly this time. “Don’t be absurd, John. Snape is not a vampire.”

John stared at him as they walked. Sherlock definitely knew more about Snape than most and certainly more that he’d ever let on.

“Are you going to tell me how you know him?” he asked finally, knowing it’s often best to be direct with Sherlock. “And don’t be a smartass and say he was your former professor,” he added, cutting the other off from saying exactly that.

Sherlock stopped as they reached the gate to Snape’s front garden. He hesitated, clearly nervous about how John would react.

John saw this in the warm light that just barely reached them. It worried him. Sherlock always trusted him, but now he looked almost scared to.

“He--” Sherlock stammered. He took a deep breath that increased John’s concern. “He looked after me in school. And a bit right before the war properly kicked off.”

John opened his mouth to ask what that meant, but closed it again when the door to the cottage suddenly swung open. Both started and looked towards the lithe man standing in the doorway.

“Well, well. Mr. Holmes.”


	5. Many Questions and Few Answers

**Summary for the Chapter:**

> John has many, many questions.

**Notes for the Chapter:**

> Sorry that this chapter took so long to get out! Life has been very busy lately, but will, hopefully, stay calmed down for a while.

An involuntary shiver ran down John’s spine at the sound of the deep, languid voice.

“Pray tell why the hell you and your pet have deemed it necessary to disturb my peace at this hour?”

They couldn’t see his face, only his form standing impossibly straight in the doorway, but they didn’t need to to know he was thoroughly pissed off.

Sherlock pulled on his most sarcastic smile. “Dear Professor, how wonderful to see you. Do invite us in for tea so we can catch up without the possibility of your Muggle neighbors waking and overhearing.”

John fully expected Snape to hex Sherlock on the spot. Which is why he was absolutely gobsmacked when Snape chuckled. The sound wasn’t completely devoid of annoyance, but it was a chuckle. From Snape. Snape actually chuckled at Sherlock when most people balled their fists.

_What the fuck is happening?_ John marveled.

Snape said nothing as he stepped back, leaving the door open for them to follow.

Now, John Watson wasn’t exactly a religious man by any means -- very few wizards were -- but the thought that he should cross himself like the Muggle Catholics flashed in his mind. He shook the idea away. Thinking of Snape in that light was childish and, obviously, quite offensive to Sherlock, though he still didn’t completely know why.

The connection between the two was, on a whole, still utterly confusing. John knew Sherlock was not exactly popular at Hogwarts despite how little the man talked about it. (In fact, the only reason John did know about Sherlock’s struggle with socializing was because of Mycroft’s strategy of taunting his little brother when he ran out of arguments.) So, it made sense that Sherlock would hold some sentiment towards the professor he claims kept an eye on him. What did not make sense was the obvious tension between them. Well, if John was honest, most of the tension was coming from Sherlock. Snape, on the other hand, almost seemed amused by Sherlock’s contemptuous attitude.

John had many, many questions.

After exchanging a quick look, John and Sherlock followed Snape inside. They entered into a small, dark living room that struck both of them as surprisingly cozy. The room was roughly the same size, if not smaller, as their own living room at Baker Street. The fireplace to their left was lit; the flickering light from the flames danced magnificently over the spines of the books that covered every wall from floor to ceiling. The furniture consisted of an ebony wood coffee table, a (slightly worn) black fabric couch, and a matching winged armchair. A few small pillows and a blanket draped neatly over the back of the couch added to the add coziness of the room.

Sherlock noted there were no pictures in the room or anything else more personal than the Slytherin bookends on the mantel. He wondered briefly if Snape kept all his more sentimental items in his bedroom.

The only window in the room was clearly where the warm light of the fire had come from.

Snape mentioned for them to sit on the couch as he seated himself regally in the winged-back chair. “To what do I owe this _monumental_ visit?” he asked, dryly, looking between the two men, though it was clear he was primarily addressing Sherlock.

Nostrils flaring ever so subtly (accompanied by a less-than-subtle eye roll), Sherlock snatched the list from an inner pocket of his jacket and thrust it towards the Potions Master.

“There are three dead Muggles, all with the same potion -- that took me a week to dissect -- found in their systems,” he explained as Snape gingerly took the list.

Snape’s brow furrowed more and more with each ingredient he read and every word Sherlock spoke. He read and re-read the list before abruptly standing up and rushing through the door directly behind the couch.


	6. Unstable

**Summary for the Chapter:**

> John remembers Mrs. Holmes told him one Christmas.

Sherlock dashed through the door -- hot on Snape’s heels; John followed close behind.

Where the living room had been lined floor-to-ceiling in books, the room the three men entered was similarly lined with hundreds upon hundreds of jarred potion ingredients. Various plants and body parts from god knows where floated in vile, almost glowing, green liquid. John’s stomach churned as he took it all in. Sherlock, on the other hand, looked downright envious.

A cauldron simmered on the long work table in the middle of the room. Green steam trickled over the top and spilled across the floor. Sherlock strode over to the cauldron to examine its contents and the ingredients strewn about the table in a chaotically organized manner that greatly resembled their own flat.

Meanwhile, Snape pulled a box out of the cupboard and began rummaging through it. His pale fingers nimbly sorted through the stacks of yellowing parchment until he found what he was looking for. Gracefully, Snape plucked the well-aged and stained roll of parchment. He strode over to where Sherlock was inspecting his potion.

“Why are you brewing Polyjuice Potion?” Sherlock asked. He barely glanced towards his former professor, but held out his hand for the parchment as he spoke.

“Because McGonagall is paying me to,” Snape sneered. He cleared a space on the table and unrolled the parchment.

Sherlock glared at him, dropping his now tightly-clenched hand.

“Don’t blow up my lab, Holmes,” Snape goaded. “I’m not in the mood to clean up after one of your little outbursts.”

John’s jaw nearly hit the floor. As far as he knew, Mycroft, their parents, and himself were the only ones who knew how unstable Sherlock’s magic could be. 

Sherlock’s mother had told him about it once at Christmas while Sherlock and his father were in the kitchen. She told him how Sherlock had started showing signs of his magical gifts at only three years of age, starting with his favourite plush owl cuddled him when he had nightmares (apparently, he had a lot).

It soon became clear to the Holmes’ that Sherlock was very powerful -- almost dangerously so. Mrs. Holmes made no qualms about how relieved they were when Sherlock came of age to attend Hogwarts and he could finally be taught to control his magic. He caught on quickly and studied hard in all his classes. (At this, Mycroft rolled his eyes in true Holmes fashion.)

The death of Cedric Diggory at the end of his Seventh Year changed all that. Sherlock became obsessed with Cedric’s death -- quickly figuring out that Harry Potter was telling the truth. Dumbledore recruited Mycroft and Sherlock to the Order of the Phoenix almost immediately. None of them were keen on Sherlock joining in on the war efforts right out of school, especially with how Diggory’s death affected him. But, of course. He was already determined to help and ignored their pleas.

Even his parents did not know everything Sherlock did and witnessed during the war -- except that he fought in the Battle of Hogwarts.

After the Battle was over, Sherlock became reclusive and unstable. He would disappear for weeks at a time (Mycroft and John both knew where Sherlock disappeared to, but they all agreed that their parents never needed to find out about his former addiction to Muggle drugs) and he became prone to outbursts that would often have destructive results.

Sherlock didn’t stabilize again until he distanced himself from the Wizarding World and began working with the Muggle law enforcement at Scotland Yard. (Mycroft never understood or approved of it, which, of course, made Sherlock more dedicated to it.) But, even then, his anger and frustration at more difficult cases -- as well as his memories of the war -- would get away from him. Luckily, he only lost control in front of Lestrade once and Mycroft was able to take care of it. Mrs. Hudson could be helpful at times, but, more-often-than-not, he was alone until he met John. Only then did the threat of Sherlock’s volatile magic blowing up Baker Street cease.

Mrs. Holmes ended her story there, teary eyed, and hugged John tight before excusing herself to the kitchen.

_He still has his moments,_ John reflected, _but the only times he’s caused more than a few purple sparks involved Mycroft. But if Snape has seen his destructive side…._

“Are either of you going to explain why you’re being even bigger cocks than usual,” John demanded, moving to stand opposite them and folding his arms, “ or am I going to have to start guessing?”


	7. The Falling Out

**Summary for the Chapter:**

> John finally gets some answers

John firmly stood his ground as he waited for one of them to start talking. Sherlock wouldn’t meet his gaze, but Snape’s glare was ice cold and deadly. That glare that put fear in the hearts of his students. The one that made Death Eaters and even Voldemort respect him. The one many believed to be permanently etched on his face. The very one that preceded most of John’s detention.

That same glare no longer had any effect on John Watson.

Years of war and years of living and working with Sherlock Holmes had hardened him far beyond what his former Potions Master’s venomous stare could do.

John stared right back, completely unflinching, with a slight cocky grin.

“I beg your pardon, Watson,” Snape growled, John’s grin pissing him off even more. “I must have misheard you.”

The brazen Gryffindor shook his head. “You heard me perfectly fucking clear, _Professor._”

Snape’s nostrils flared. “You’ve somehow managed to become even more intolerable than you were as a student.”

“Thank you.”

Another tense moment passed in which Snape stewed in silent fury.

“John, leave it,” Sherlock spoke up. The other two were slightly taken aback by his request, but they did not break eye contact.

“No, Sherlock,” John responded. “You told me Snape looked out for you in school and that you were the one that set all of this up so that he could have some peace after the Second War. But you have been on edge since we left Baker Street and it’s only gotten worse since he opened the fucking door. And, he is acting the same way towards you despite his obvious interest in helping with the case. So, one of you is going to have to spill it or we are never going to make any headway with this case because you two will be too busy bitching at each other. Now, spill it!” John’s voice was now at a dangerous level.

Sherlock shifted, but said nothing. He was incredibly uncomfortable and anxious, and didn’t know what to do; John could see this, but he could also see that Sherlock knew he was right. He hated watching his friend in such turmoil, trying to decide between self-preservation and solving the most interesting case they’d had in weeks, but he couldn’t let up. Forcing the source of their tension to the surface was not only what was best for the case, but for Sherlock as well.

Meanwhile, Snape stood seething at the blatant disrespect John had paid him; his own anger rising with every decibel of John’s voice. “Very well,” he spat. “I’ve kept enough secrets for ungrateful brats.”

Sherlock cut his eyes at him, but didn’t take the bait.

Snape let the parchment roll backup and stood straight, folding his arms with the parchment secured in his right hand. “It’s quite simple really,” he hissed at John. “Quite opposite yourself, your dear friend here was truly the most brilliant and talented student I ever had. He could have been an auror or a Potions Master or Defense Against the Dark Arts professor. He could have been absolutely _anything_. However, he chose to waste his brilliance on solving Muggle crimes. And when I expressed my… _disappointment_ in his decision, he lost control, nearly blowing _me_ up, and vanished. I never saw or heard from him again. Even Holmes the Elder seemed pissed off at me for the incident, but refused to explain why.

“After quite some months of hearing nothing, I moved on with my life. That is, until the two of you decided to grace me with your presence at this _glorious_ hour.” His closing statement was growled through clenched teeth.

Sherlock stood rooted to the spot, visibly shaking. 

John looked to him now, taking in how lost and upset he appeared. His frustration faded and worry took over as something Snape said hit him.

“Sherlock, where did you go?” John breathed, afraid he already knew the answer.

Snape’s brow furrowed, turning his attention to Sherlock as well. The sudden shift in John’s demeanor had taken him completely off guard.

The detective tentatively met John’s gaze. “You know where,” he answered, barely above a whisper.

John sighed and nodded solemnly.

Snape looked between them. “Care to explain?” he demanded when neither of them elaborated.

John watched as Sherlock flexed his jaw and looked at his shoes. He looked every bit like a First Year being chastised by his professor. “A drug den,” he finally admitted even quieter than before.

Snape’s face fell, his eyes wide with shock.

“Mycroft found me two weeks later,” he continued. “At least, that’s how long he said it had been when I woke up in that Muggle hospital.” Sherlock caught John’s eye again before saying in a shaky voice riddled with shame, “That was the first time that I overdosed.”


	8. A New Lead

**Summary for the Chapter:**

> John and Sherlock finally get a lead and Snape learns something about his former student that is hard to swallow.

Silent tension hung in the air like a heavy winter blanket; Sherlock felt like he was suffocating under it. He looked between John and Snape, withing for one of the to _just fucking say something!_

John was clearly trying not to react too strongly to this new information. (After all, Sherlock’s history of addiction was no news to him -- though the details many have been kept vague.) But his subconscious habit of fidgeting his thumb over his white-knuckled fist gave him away to his all-too-observant friend.

Snape, on the other hand, simply stared at him with an expression of pure shock that only made the room seem more stifling.

Getting Snape to show any kind of true emotion was difficult and cause for concern, but this...this was completely new territory.

Sherlock had seen him angry -- even furious -- countless times. Annoyed and sadistically entertained were also up there. But those were rarely displayed without regulation and to see any emotions more personal or sentimental was almost unheard of.

All those years serving as Dumbledore’s spy, keeping his guard up and cover secure, had drilled him into a lifestyle of constant self-preservation.

But, now, it was like he’d completely forgotten how to wear that hardened mask that had become so ingrained into his very being. Sherlock didn’t know how to handle that, and -- obviously -- neither did Snape.

“First time?” Snape tentatively asked, like he’d spent the whole period of silence debating with himself whether or not he’d heard Sherlock correctly and hadn’t reached a verdict.

Sherlock shuffled his feet, still looking like a scolded child. He nodded minutely. “Yes.”

John watched on as the full gravity of what Sherlock was saying hit Snape.

“How many?”

Sherlock hesitated before answering. “I’ve overdosed a total of 4 times, alright? Now can we, _please,_ get on with the case?!”

Snape nodded curtly, looking completely gobsmacked. He clearly had more to say on the matter, but -- to Sherlock’s obvious relief -- decided against it.

Without another word, Snape stepped forward and unrolled the parchment scroll on the table again. This time, however, he left enough room for Sherlock to stand beside him and read it. The latter studied him for a moment before stepping forward to examine the parchment.

John leaned over the table to read it as well.

“It’s almost the exact same list,” Sherlock exclaimed, a look of disbelief pulling his features together. “Where did you get this?”

"From a student,” Snape answered. “Margery Kentworth. Brilliant and gifted student -- at least at Potions, anyways. And one of the nastiest Hufflepuffs I have _ever_ met.”

“How do you mean?” John asked.

“Kentworth liked to experiment when she decided she had nothing better to do with her time,” Snape explained. “She quickly realized -- as did the staff -- that she had a talent for creating stable, effective potions. It started rather harmlessly, I suppose, with healing potions for minor abrasions and ones that did things like dye almost all of the Gryffindors’ hair green in her third year. But she quickly became bored of those.

“It was only her fourth year when she poisoned a student for the first time. However, the young man -- a Ravenclaw Second Year, if I recall correctly -- only got something like a flu and we could not prove it was her, though we all knew it was. Despite our arguments for it, Dumbledore refused to expel the little psychopath without evidence. You would have thought she was a Potter for the way he turned a blind eye to her actions.

“Two more students were poisoned before she quit school after her fifth year. Again, we could never prove it was her, but the condition of her victim was worse each time.”

“Do you know what she did after Hogwarts? Or where she might have gone?” John asked as he finished his notes on this new information.

Snape shook his head. “No. I suspect Dumbledore did -- the Dark Lord, as well -- but I never heard anything about her again.”

John added this to his notes, then turned to Sherlock. He frowned.

Sherlock was staring into deep space, his fingers steepled in front of his face.

He knew that look. 

“What is it, Sherlock?” He mentally kicked himself for sounding like a Muggle cartoon character.

“I’m not sure,” Sherlock answered in a distant voice. Abruptly, he snatched up the parchment, scanning it several times before blurting out, “I need to go to my mind palace!”

John knew better than to even reply in acknowledgement of this statement. He walked towards the door and opened it. 

“Come on, Snape,” he called back, stopping a very confused Snape from talking to Sherlock.   
They exchanged a look. John jerked his head towards the living room.

Understanding, Snape followed (though he did not look pleased by John giving him more orders).

They left as Sherlock perched himself up on a stool, steepled his fingers again, and closed his eyes, disappearing into his mind palace.


	9. Noire Morales

**Summary for the Chapter:**

> A new addition to the team arrives and Sherlock finds what he was searching for in his Mind Palace.

**Notes for the Chapter:**

> This chapter is much longer than normal, but it's one of my favourites so far!

John closed the door behind them. He crossed his arms in a casual manner as he turned to Snape. “Do I need to explain?”

Snape crossed his arms in a less casual manner -- letting John know that he was definitely still pissed about being shouted at and ordered around by his former student. “No, he’s always used his mind palace. Mycroft has one as well, though I don’t think his literally took the form of a palace like Sherlock’s.”

John chuckled. “Weird, I’ve never thought about Mycroft as a student. Jesus, he must have been a right twat. Did he already have a god-complex then?”

No reply. Snape continued to glare down at John, but gave no indication of an answer to his question.

The Gryffindor laughed to himself. (He knew laughing out loud would be pushing it.)

“You’re not one for small talk and reminiscing are you?” he asked.

Again, Snape said nothing.

John sighed. He wasn’t afraid of the former Potions Master, but he did respect him. This man wasn’t just his old professor, he was the spy that managed to protect Harry Potter and undermine Voldemort from behind enemy lines and all while the Order -- including himself -- hunted him down and the other Death Eaters tried to get rid of him by any means possible.

For the first time since they arrived, John really took in Snape’s appearance. He looked tired, even more so than when John was a student. Like he hadn’t slept since the end of the war. It was nearly 3 a.m. when they got here, but Snape was still in his day robes. His clothing was quite similar to the ones he always wore: black with many buttons and layers. But now there was a light, black scarf tied around his neck. It was loose on one side, as if he messed with it a lot. 

Sticking out ever so slightly on that side was the top of a gnarly looking scar.

_It may have been the only way to get them to stop bitching at each other,_ John thought, _but he didn’t deserve that disrespect._

“Look,” he began awkwardly, “thanks for helping us with the case and all.” He paused, looking for any kind of reaction.

Snape’s eyebrow hitched in such a way that John could actually hear “go on” in his voice despite the fact that his lips were tightly shut.

“And I’m sorry,” he continued. “For intruding so late at night. And for the way I spoke to you earlier. All that needed to come out so Sherlock could focus on the case -- and not blow up your lab. But it was completely uncalled for and I apologize.”

Snape glared into his soul until John started to wonder if he was going to be hexed.

Finally, Snape turned away and started walking towards the kitchen. “Tea?” he called back over his shoulder.

Before he could answer, there was a knock at the door.

John’s head snapped towards the sound. He reflexively drew his wand.

Snape reappeared at his side, gripping his own wand. They exchanged a look.

“Do you sense that magic?” John whispered.

Snape nodded.

Another knock. A rather impatient one, this time.

They started forwards, John putting himself in front of Snape as they approached the door. He looked at Snape and gestured towards the handle.

Understanding, Snape cautiously grabbed it and -- after John nodded -- yanked it open.

John thrust his wand under the newcomer’s chin.

“Really, Dr. Watson? Is that _completely_ necessary?”

“Mycroft?!” John stared at the elder Holmes in unabashed disbelief. “What the _hell_ are you doing here?”

“Well, I believe that’s quite obvious, don’t you think? Even for you.” He tapped John’s wand, which was digging into the soft skin under his jaw after that last insult. “Do you mind?”

John lowered his wand, gritting his teeth.

“Thank you,” Mycroft smirked. He pushed past John without waiting for an invitation.  
He looked around momentarily with a curious expression before acknowledging Snape, holding out a hand to him. “Nice to see you again, Severus. Long time no see.”

Snape crossed his arms again, fuming. “Do _not_ call me that name, Holmes. But do explain _exactly_ why you’re here. Given what I’ve read of the Consulting Detective and Dr. Watson, your assistance -- though I doubt that’s what this is -- is not normal.”

_He’s read about our cases?_ John pondered. _Has he been keeping tabs on Sherlock?_

Mycroft sneered, flexing his hand as he dropped it. As much as he hated showing true emotions, it was very obvious when his ego was damaged.

“Yes,” he replied, not agreeing to anything in particular. “Very well. I’ve been put in charge of making sure this case is solved and covered up in a timely manner. I don’t believe I need to explain the severity of the situation what with three muggles having been murdered by a wizard with an experimental potion. Things would get very messy for out kind.”

Snape breathed a short laugh. “I rather thought it already was.”

John couldn’t help but laugh at that.

Mycroft clenched his jaw.

“NOIRE MORALES!” Sherlock burst into the living room, shouting in a french.

All three men turned to face him, each wearing an expression of shocked confusion.

Sherlock locked eyes with his brother and stopped dead in his tracks. The wild look of building triumph faltered slightly. “What the fuck are you doing here?”

John put his hands up, stopping whatever sarcastic jab formed on Mycroft’s sharp tongue. “Nope, we don’t have time for that. Sherlock, what is ‘noire morales?’”

Sherlock eyed Mycroft for another moment before deciding to leave it alone. “It’s a calling card disguised as a name. I’ve come across it a few times over the years in cases involving potions, but none of them were of much substance. Boring stuff that took even the Ministry and its minions minimal effort to deal with. The cases were never interesting so I never followed up on them, though I always believed that those cases were just a warm up. Just practice. I shared this with the Ministry and they assured me they’d keep tabs on it.” He locked eyes with Mycroft once more. “But clearly they have not.”

For the first time ever, Mycroft did not take the opportunity to bite back. Quite oppositely, he was listening intently and seemed to agree. “It makes sense,” he said. “But are you sure this is the same person?”

“Yes. From what Snape told us about Margery Kentworth and this potion of hers--”

“That potion is the doing of Margery Kentworth? I knew she should have been dealt with sooner.

Sherlock gave him a pointed look. “Do you mind?”

Mycroft held up his hands. “Sorry.”

Rolling his eyes, Sherlock continued, “She’s cruel and cares little for the lives of others. However, she’s never actually killed -- at least, not that we know of. The major commonality in the Noire Morales cases was that that was the name the attackers gave as their supplier. There was only one other that I suspected to be by the same potioneer with no middle-man, but it was fairly harmless. Not interesting at all. I passed on the information as well as my theory, but did not pursue it.

“That potion is far more refined than the original scribbled concept that you showed us, Snape. But it still isn’t perfect. Meaning, it’s better from improved general skills, not from actually practicing the potion itself.

“You said Kentworth’s motivation was to alleviate boredom. What if she got bored of testing minor illness potions and selling them? What if a client asked for a potion to kill Muggles, and she was finally so bored that she agreed and decided to recreate her school-hood brainstorm to see if it would actually work.

“It even fits the name. ‘Black Morals.’”


	10. Bickering Brothers

**Summary for the Chapter:**

> Mycroft and Sherlock bicker with each other until Snape puts his foot down.

Sherlock looked between the other three men as they processed this information and considered his theory. John was the first to speak.

“I agree,” he said. “It all makes sense.”

“And hiding behind an alias would explain how Kentworth managed to disappear after Hogwarts,” Snape added. He tapped his forefinger to his chin as he thought.

Sherlock nodded, enthusiastically. “Precisely!” He shifted his gaze to his older brother -- the man with both the Wizard and Muggle governments in Great Britain in the palm of his hand. “What do you think, Mycroft? Does it fit?”

Mycroft broke from his train of thought, his hand dropping from the side of his face. He met Sherlock’s eyes. “Yes, I believe it does.” An odd look flickered in his eyes at Sherlock’s expression of triumph, but it quickly disappeared as he continued. “In fact, I’ve believed Margery Kentworth to be Noire Morales for quite some time. Unfortunately, there was never enough proof. She always managed to cover her tracks -- nothing could ever be traced back to her. I do hate it when they are _just_ clever enough.”

“The aurors couldn’t find a connection?” John asked, baffled. “How could they hunt down the most skilled and dangerous Death Eaters after the war, but not one potioneer with a weird hobby?”

Mycroft rolled his eyes. “Have you not been paying attention at all?”

John clenched his teeth, trying to think of a solid reason not to hex him.

Seeing the anger on his anger on his face, Mycroft sighed and explained. “None of the incidents were all that troublesome. The supplier -- while, perhaps, questionable and annoying -- was no real threat, even if they did know what their potions were being used for. It was certainly not enough to be considered a Dark Wizard. And, therefore, not enough to get the aurors involved.”

Sherlock looked offended. “Why didn’t you bring it to me?”

“Because, as you have so thoroughly addressed, it didn’t interest you,” he retorted with a sarcastic smile.

_Oh, here we go,_ John thought in exasperation. He rubbed his sleep-deprived eyes as the two brothers began bickering.

“You bring me boring cases all the time!”

“Which you either make John solve for you or you completely ignore. You refuse to answer to anyone, but you are especially stubborn and petulant when it comes to me.”

“What the hell is your point, _Mycroft?_”

“Exactly what I said!”

“Ugh! You are so distracting!”

“Enough!” Snape growled. He didn’t yell -- he didn’t have to. The menacing tone of his voice was sufficient to immediately silence them. “There will be plenty of time left in your lives to continue this incessant squabbling _after_ the matter at hand as been dealt with. Per the moment,” he paused to level Mycroft with a steely gaze that demanded the absolute truth, “where does she live? If you have indeed been keeping up with Ms. Kentworth, as you say, you must know where to find her.”

Mycroft sneered. “As there’s no point in lying to a Legimens….”

Snape raised an impatient eyebrow. “Go on.”

“Promise me you can prove this is Kentworth’s doing beyond a doubt,” Mycroft stiffly implored Sherlock. “She can’t be allowed to get away again. Not this time. Not as far as she’s gone now.”

Sherlock nodded, slightly taken aback, but trying not to show it. He knew this was no simple request to help take down a criminal. Mycroft was asking him to accomplish what he’d failed to do for years. It would put a criminal behind bars, yes. But it would also protect Mycroft’s position and reputation.

He stood tall and looked his big brother in the eye quite differently than he had before. “I will stop her, Mycroft.”

“Very well,” Mycroft replied.

As he faced Snape again, John could have almost sworn there was anticipation in his eyes. But, for what, he could not have predicted in a million years.

“Kentworth’s current address is 42 Rosemary Drive...in Godric’s Hollow.”


	11. The Catalyst

**Summary for the Chapter:**

> A plan is made.

Snape’s whole body went rigid -- more so than usual and certainly more than most of them had ever seen. His eyes lost focus, as if he was suddenly somewhere else, seeing something that wasn’t there in the little Welsh cottage. Sherlock watched the colour drain from his features with unaccustomed apprehension.

“Godric’s Hollow?” John repeated. “Why do I know that name?” He tried to pinpoint where he’d hear it, but he couldn’t. Everything that came up felt fuzzy and isolated by large blank spots. It had to have been from when he was a young kid.

Mycroft did not respond, seeming almost too afraid to speak lest he make Snape’s current state worse.

Their roles now reversed, Sherlock bore the same expression Snape had after learning about Sherlock’s extensive history of addiction.

Not taking his eyes off of Snape, Sherlock filled in the blank spots. “Godric’s Hollow,” he started in a soft voice usually reserved for the most critical of clients and victims, “is where James and Lily Potter were murdered by Voldemore on October 31st, 1981. And where Harry Potter was marked by him as the Chosen One that same night. The catalyst for the Second Wizarding War and end to the suffering Voldemort -- and his little henchmen -- inflicted upon the world.” He hesitated a moment, carefully calculating the situation and his next words. “It’s where so many lives were changed..._permanently._”

He took a few steps towards him. “Professor?”

Snape’s eyes came back into focus. He regarded Sherlock with a guarded mask of neutrality so well built it was all but physically manifested on his hardened features.

Unphased, Sherlock pressed on. “I know the last thing you ever want to do is step foot in that village again. But we can’t do this without you. We need you to help us bring Kentworth to justice once and for all, and this killer along with her.”

John and Mycroft watched on in unabashed amazement as Snape’s mask cracked and fell away.

Fists clenched, he nodded to Sherlock. “Then you leave me alone, he added with his signature smirk.

Sherlock chuckled. “Yes, then we will leave you to enjoy your retirement in peace.”

Once again confused, but knowing they were running out of time, John inquired, “So, what’s our plan then?”

“You, me, and Snape are going straight to Kentworth. I have an idea of how to get her to confess, but we must do it quickly before she figures it out or flees. Mycroft will meet us there with Aurors in exactly half an hour.”

Mycroft clearly did not like taking orders from Sherlock, but he said nothing.

“Fine, then,” Snape said, steeling himself and taking out his want. The other followed suit. “No more time to waste.”

With four loud, synchronized cracks, they Disapparated.


	12. A Mission to Forget

**Summary for the Chapter:**

> Sherlock tells two stories about the history of Godric's Hollow.

A shiver ran down John’s spine as they appeared on a dark, empty street that had nothing to do with the frosty air. He could feel the ancient, dark magic permeating this place in his very core. Any wizard that stepped foot here would have to have felt that horrible things had happened here, even if they’d never heard of it before or stumbled upon it by accident. It wrapped around them and made its presence known, like a heavy, weighted blanket -- but without the comfort.

And yet, it looked so normal. By all appearances, this was just a quaint little Muggle village, no different from any other modern country village. Street lamps broke up the grey darkness of the pre-sunrise hour with warm light. Cars dotted either side of the street. Every house could see around them was old and obviously full of history, despite evidence that they were well taken care of. They clearly showed that the locals had pride in and loved their village. A few of them even had Christmas lights up already.

But John could not shake that eerie, haunted feeling.

“You can feel it, can’t you?” Sherlock asked, having observed John’s discomfort as he took in his surroundings.

“What?” John knew exactly what he meant, but he needed Sherlock to be the one to say it.

“The dark magic,” Sherlock breathed. “A lot of it. It’s often the first thing wizards notice when they come here. Not all wizards, mind you, but most. The first time I came here, it was all I could do to focus on anything other than the oppressive evil that lingers in the atmosphere.”

Snape, meanwhile, was visibly becoming more agitated. His knuckles were bright white from the way he was strangling his wand.

Noticing his unease, Sherlock set off at a controlled, brisk pace. “Come,” he said. “We’re only a few streets away/”

John and Snape fell into step on either side of him.

“The Potters’ murder wasn’t the only thing that happened here, was it?” John guessed.

Sherlock cut his eyes towards Snape for a split second before answering. He expected a reaction to John’s blunt words; yet, he wasn’t surprised when he saw none. “No, it wasn’t. Several things have happened here. For instance, this is not only where Dumbledore grew up, but Godric’s Hollow is also where he first fought the dark wizard, Gellert Grindelwald. During which, his little sister, Ariana, was accidentally killed in the crossfire. Both were using dark magic -- including The Killing Curse. Whether he ever figured out which of them killed her, no one knows. At least, not to my knowledge.” He looked to Snape, wordlessly asking for confirmation or correction.

_God, you’re such a Ravenclaw,_ John thought. _In your thirties and still teacher’s pet._ He suppressed a chuckle.

Snape shrugged. “He never really spoke about it. Maybe a murmur here or there towards the end when he knew he was dying from the curse on the Gaunt Ring horcrux. He became obnoxiously sentimental and forlorn, then. _For the things that mattered to him, anyways._” The last sentence was spoken through his teeth. He shook his head briefly to regain composure. “But I never heard him specifically say he learned the answer to that particular mystery. I don’t think it mattered to him -- he blamed himself, either way.”

Suddenly, something Sherlock said earlier clicked in John’s head.

“Hold on. You said, ‘the first time’ you came here,” he said, frowning. “But you’ve never mentioned Godric’s Hollow to me.”

Sherlock paused before answering in a forced tone. “Neither of us speak much about the war.”

Snape almost stopped dead in his tracks. “Why were you here during the war?” he demanded, sounding mostly bewildered, but with a definite amount of concern underneath as well.

Annoyed that the subject was not going to be dropped, Sherlock sighed, glaring at the street ahead as they continued walking. “Lu- Lupin sent me. For the Order. He’d heard of a strange disturbance here in a brief story on a Muggle radio, just in passing, and then nothing else about it. Obviously, he was familiar with Godric’s Hollow, given his friendship with the Potters. It struck him as odd -- he never believed in coincidences. So, he sent me to check it out and told me not to say anything about it to anyone. He thought it might have something to do with what Harry Potter and the other to were up to. As protecting Harry Potter was the highest priority for the Order, even though we had no idea where he was or what he was doing, I was to cover it up if I found any evidence of them.

“Immediately upon arriving, I could sense Potter and Granger’s magic as well as a lot of dark magic -- both old and new. I followed it to a house that had clearly been a battleground, where I did find evidence of both Potter and Granger -- and Bathilda Bagshot’s horrible mangled corpse.

“After sending a Patronus to- to Lupin to tell him what I found and to ask for assistance, he sent Mycroft and we covered it up. Besides a debriefing with him when we returned, we never spoke of it again.”

All of this was spoken at a rapid fire pace. Normally, this speech pattern was because his mouth was trying to keep up with his brain. But this time, it was different. This time, it was more like he needed to get the words out as quickly as possible.

John and Snape reeled from this flood of information. Neither of them knew how to respond, but they wouldn’t get the chance to figure it out just yet.

Sherlock signaled for them to be quiet as they turned a corner and went to the second house on the right.


	13. One Nasty Hufflepuff

**Summary for the Chapter:**

> John, Sherlock, and Snape confront Kentworth.

Following Sherlock’s lead, they put their wands in their pockets. John and Snape kept a hand on each of theirs, but Sherlock left both hands free, trusting the others to have his back.

The house he lead them up to looked just as normal and mundanely Muggle as all the other houses on Rosemary Drive. Small, solar-powered garden lights illuminated the pave-stone sidewalk that ran through the neatly kept lawn. A few brown leaves were scattered here and there, and a small garden that must have been quite impressive in the summertime preceded the quaint porch. A metal 42 in elegant script adorned the front door.

By all appearances, they were walking up the steps to the home of a very social and domestic Muggle family. It certainly didn’t appear to be the home of someone who deliberately invented a deadly potion and supplied it to a murderer.

According to Mycroft’s intelligence, however, that’s exactly what it was.

Sherlock bounced right up to the door as if he was paying an old friend a visit. He knocked three times and poised himself near the door, just enough to be seen through the peephole, while still being abnormally close.

Lights flicked on on the second floor, the stairs, and -- finally -- the foyer. After a few moments in which Kentworth was, presumably, looking through the peephole and assessing the situation, the door slowly creaked open a few inches.

With the speed of a striking cobra, Sherlock’s hand shot out, forcing the door completely open and took a step inside. Kentworth took an even step back, a shocked expression flashing across her face before quickly receding again.

He took a few more steps, which she compensated for to keep the distance between them, creating room for John and Snape to enter, wands drawn by their sides. Snape closed the door behind them, eyes fixed on the woman he’d deemed as “one of the nastiest Hufflepuffs” he’d ever met at such a young age.

Now that they were inside, John could get a proper look at her.

Margery Kentworth was on the shorter side, roughly 162 cm tall, though you would not know it from the confident way she carried herself. Her curly, blonde hair -- _definitely not her natural colour,_ John noted -- was tied up in a messy bun. Given her attire, they’d definitely definitely woken her up; black sweatpants, a wrinkled grey tank top riddled with what looked like potion stains, and a black robe screamed of the early morning far louder than she ever could vocally. 

She had a cool, indifferent demeanor, but, after years of living with Sherlock, John quickly saw that this was calculated. He could practically see her figuring out what was happening and running through her options -- just like Sherlock does on a crime scene.

Unlike Sherlock, however, she seemed to be coming up empty.

Desperately, she fixed her attention on a familiar face. “Such a pleasant surprise,” she said in a flat voice. “I had my fantasies about you, Professor, but I must confess I never expected you to be the type to bring company.” She gave Sherlock and John a once-over. “Though I’m not complaining -- you have good taste.”

Snape glared at her, lip curled into a snarl.

Eyes the size of Mrs. Hudson’s doilies, John’s face convulsed in a mixture of shock, horror -- and a little bit of anticipation of how Snape would respond. This might be his only chance to witness one of Snape’s legendary, invented spells first-hand.

Unfortunately, that wasn’t part of Sherlock’s plan.

The notoriously impatient detective hummed his annoyance. “Sorry, I don’t do well not being the center of attention of attention. Especially when I’m winning.”

_At least he knows it,_ John thought, slightly disappointed.

“I’m sure I don’t know what you mean, Mr., um....” she feigned.

Sherlock rolled his eyes, grinning wickedly like a wolf that’s cornered it’s prey -- or a consulting detective who’s cornered an elusive criminal. 

“Oh, don’t play stupid with me, Kentworth,” he started. His speech pattern picked up speed with every word. “You know exactly who I am. A fact that was made quite clear by your momentary hesitation between when looking to see who was at the door and when you finally opened it. You gave yourself time to compose yourself _after_ placing your hand on the doorknob. Very quick, hardly noticeable -- to anyone but me. Then, of course, there was your biggest mistake: looking past me. Passing off your attention to Professor Snape, making him angry and uncomfortable in a sad attempt to buy yourself time to come up with a plan to weasel yourself out of this. But I don’t think I have to tell you that your efforts are pointless -- there’s no way out. And I suspect you knew that from the instant you recognized me.

“Given how long you’ve been at large, in business with your little outlaw potioneering, you’ve been quite good at covering your tracks. No one could prove you were responsible, not even my own brother, Mycroft Holmes. But you made a mistake. You couldn’t resist using the potion you’d developed in school -- the one that put you on the staff’s watchlist. The one you’ve obsessed with ever since. What could it hurt? It was _finally_ perfected and you were dying for someone to give you a reason to test drive it. Surely, no one would recognize it? It was so long ago. So much has happened since then.

“And then some poor fool comes along, looking for a way to get rid of some pesky Muggles. You finally have the perfect chance to test out your brain-child with no repercussions. Their deaths would be labelled as mysterious by the Muggle authorities -- possibly even covered up by the Ministry even if they can’t identify the potion. The case would go cold and no one could prove the potion was yours. Except me.

“You didn’t anticipate the wizard who worked with Muggle law enforcement as a consulting detective. Nor could you have predicted that we’d get in contact with the very professor that first raised concerns about your little hobby.

“_God,_ I hate it when interesting cases turn out to be so boring!”

Kentworth shook like a trapped rabbit, flinching when he raised his voice with his last sentence. They could see desperation and panic written all over her face as she tried and failed to think her way out. She was defeated and she knew it.

John had the urge to check his watch -- to see how long they had before Mycroft shows up with the Aurors -- but he resisted, knowing it might give them away. It did not slip past him that Sherlock mentioned Mycroft’s name, eliciting a startled flash of recognition, but did not mention his impending arrival.

Suddenly, a spark ignited in her eyes. “But you don’t know who I sold the potion to,” she countered. “That’s why you’re here. Otherwise, you would have just sicced your brother and his dogs after me.” She crossed her arms defiantly. “That gives me leverage. You haven’t won yet. And I would much prefer if you didn’t.”

Sherlock allowed a poignant pause, making a show of studying her and considering her words.

John and Snape exchanged a knowing look -- she was playing right into his hand.

“Go on,” Sherlock encouraged, crossing his arms as well to mirror her posture.

“I want a deal: I give you his name and you let me go. Tell your big brother I wasn’t home, trail went cold.”

“And why would I do that?”

“Because it will be more interesting for you.”

Again, Sherlock pretended to consider her words. “Fine. You have my word. Now, give me his name and anything else you know.”

She hesitated a moment, looking for signs of trickery from any of the men in her foyer, before deciding to take Sherlock’s word. Her shoulders relaxed.

“Amadeus Klint. Fairly ordinary. Didn’t say much about himself. None of them do ‘cept a few stray, lonely morons. Said he needed a potion to take care of some Muggles, his neighbors. He’s a mumbler, so I didn’t understand much of what he said, but -- from what I could understand -- they disrespected him...in some way. As well as just being annoying. He repeated that last part several times.”

The air left John’s lungs.

“You supplied a lethal potion to someone because their neighbors were _annoying?!_” Snape seethed, completely horrified.

Kentworth shrugged, clearly excited to have another opportunity to mess with him. “Sorry to disappoint you, professor. I’ll be happy to make it up to you,” she said with a wink.

With an emphatic flourish, Sherlock checked his watch. “Fortunately, I’m afraid there’s no time for that.”

Half a dozen loud cracks ripped through the air. 

Kentworth whipped around the door burst open and five Aurors surrounded her. Mycroft was right behind them, vindication exploding across his face when he saw Sherlock’s smirk.

“YOU GAVE ME YOUR WORD!” she screamed.

Sherlock pulled an expression of mock regret. “I lied. My way is _far more interesting!_”


	14. A Final Surprise

**Summary for the Chapter:**

> With the case solved, Sherlock, John, and Snape head back to Baker Street.

**Notes for the Chapter:**

> I can't believe this is already the final chapter! There are so many feeling going on inside my head right now. Thank you so much for the support on this series! It was so much fun to write!

Kentworth continued to scream at Sherlock as the Aurors made the arrest, calling him -- and John, Snape, _and_ Mycroft -- every insulting name there is...and more. He ignored her.

“You’re looking for Amadeus Klint,” he told Mycroft, talking out his mobile and texting him everything they’d been told in detail. “No doubt he’ll squeal like a pig the moment you pick him up, if he doesn’t turn himself in first.”

“Why don’t you just write it all down?” Mycroft sneered as his pocket buzzed, prompting him to pull out his own mobile.

Sherlock rolled his eyes. “I just _did._ Don’t pretend you’re not addicted to your mobile or prefer its convenience. There’s no bottle of ink rattling in your coat either.” He tapped on another name and paused, thumbs poised. “What information should I give Lestrade?”

He was still still speaking very fast. His part -- the interesting part -- was over; he’d solved the case. The rest of it was boring and tedious, and took away from the time he could spend looking for a new case. As always, the faster he passed off this case, the better. For everyone.

“The name, that I’ve ordered the arrest, and that I’ll contact him later today to give him later to give him what he needs to take credit for the arrest.”

Sherlock’s thumbs flew as the older Holmes spoke. Without another word, he walked out of the house as he hit send and returned the mobile to the pocket of his trench coat.

John nodded briefly to Mycroft before following Sherlock with Snape right behind him. When they fell back into their paces on either side of him, he abruptly grabbed each of their arms and Disapparated.

~ ~ ~

“DAMMIT, SHERLOCK! I told you not to do that without warning people!” John complained in a tone that said this was definitely not his first surprise Apparition. He held his hands on either side of his head while the world slowly stopped spinning.

“Sorry!” he replied, exasperated. “I honestly meant to...this time.”

“Well, you didn’t!”

“Evidently….”

Snape, meanwhile, had regained his equilibrium a bit faster than John, though he was no less annoyed. But, deciding John needed no help in scolding Sherlock for his lack of etiquette, he, instead, took in his surroundings. He took in the drab alley they’d appeared in, the harsh light of the street lamps offset by the dim rays of the rising sun that found their way between tall buildings, and the hellacious cacophony of noise.

London.

“Is there a reason you brought me to this dreadful city?” he asked, nose wrinkling as the smell from the banged-up alley bins reached him.

Sherlock nudged a now sure-footed John forward to lead the way back down the street they’d taken so many hours. “Yep, tea.”

~ ~ ~

Discarding his coat in the general direction of its hook, John stumbled into the kitchen to make a pot of ungodly-strong coffee. Sherlock and Snape hung up their coats (Sherlock pausing to pick up John’s and hang it properly) before dropping into the two armchairs.

With an absentminded snap of Sherlock’s fingers, flames flickered up and steadily grew in the fireplace.

Snape took careful note of this as the detective closed his eyes and finally relaxed for the first time in over a week.

“You know,” he said in a calculated tone, “I was wrong about you, Holmes.”

Sherlock’s eyes shot open, brows furrowed and nose scrunched, unsure of what he’d heard or if he’d even heard Snape correctly. In the kitchen, John dropped his sugar spoon.

“What?” Sherlock managed nearly a full minute after the word formed on his lips.

Snape rolled his eyes. His body was tense, clearly uncomfortable with what he was about to say. But he powered through.

“I was wrong,” he repeated, still using the same tone. He caught Sherlock’s eye and held it. “We saw an _absolute_ waste of talent tonight. You’re not it.”

John saw his own shock on Sherlock’s face -- and so much more.

“Oh-ho! You’re awake!” a cheerful voice exclaimed accompanied by the clattering of her tea tray. “I was sure you boys would have been to bed by now.” She stopped when she realized it wasn’t John sitting across from Sherlock. Recognition nearly took her breath away.

Sherlock jumped up to take the tray from her, placing a chaste kiss on the top of her head. “Thank you, Mrs. Hudson,” he said, more for the timely interruption than the tea. “You’re a lifesaver!”

Collecting herself, she giggled at the rare show of affection. “Oh, Sherlock! I’m sorry, I didn’t know you’d brought home company. Shall I get another cup for you, Severus?”

_At this point, our eyebrows may as well be stapled together,_ John thought, once again seeing his confusion and shock mirrored in Sherlock’s features.

“It’s alright, Mrs. H.,” John answered for him, brandishing the coffee mug he was stirring (with a new spoon). “I’m good. He can have mine.”

“Alright, dear,” she said. She dropped a cube of sugar in one of the tea cups and splashed in some cream. “I hope you still take your tea the way you used to,” she added, handing it to Snape.

“Um, yes. Thank you,” he managed. A defensive scowl was setting in, almost like a reflex.

“I know I’ve said it before, dear,” she chastised him, “but it wouldn’t kill you to smile once in a while. Honestly, Severus, I would blame you for Sherlock’s moods -- if I didn’t know his brother. Compared to Mycroft, Sherlock’s a bit of a peach, really.”

Laughing to herself, she left the apartment.

The three men stared after her in bewilderment.

“Will she ever stop surprising us?” John asked Sherlock.

“God, I hope not.”


End file.
